Nematic liquid crystal composition and liquid crystal display element using the same

ABSTRACT

The nematic liquid crystal composition exhibits a positive dielectric anisotropy (Δ∈), the liquid crystal composition being useful as a liquid crystal display material, and a liquid crystal display element using the same. The liquid crystal composition of the present invention has a large absolute value of dielectric anisotropy thereof and a low viscosity. By using this liquid crystal composition, it is possible to provide a liquid crystal display element which has a high contrast, high-speed responsiveness, and good display quality in which image sticking and display defects are not generated. The liquid crystal display element using the liquid crystal composition is a useful display element which realizes both high-speed response and suppression of display defects. In particular, the liquid crystal display element is useful as a liquid crystal display element for active-matrix driving, and can be applied to, for example, an IPS-type or TN-type liquid crystal display element.

TECHNICAL FIELD

The present invention relates to a nematic liquid crystal compositionthat exhibits a positive dielectric anisotropy (Δ∈), the liquid crystalcomposition being useful as a liquid crystal display material, and aliquid crystal display element using the same.

BACKGROUND ART

Liquid crystal display elements are used in not only watches andelectronic calculators, but also various measuring instruments, panelsfor automobiles, word processors, electronic notebooks, printers,computers, televisions, clocks, advertisement display boards, etc.Typical examples of a liquid crystal display system include a twistednematic (TN)-type display, a super-twisted nematic (STN)-type display, avertical alignment (VA)-type display using a thin-film transistor (TFT),and an in-plane-switching (IPS)-type display. It is desired that liquidcrystal compositions used in these liquid crystal display elements bestable against external factors such as moisture, air, heat, and light,exhibit a liquid crystal phase in as wide a temperature range aspossible with room temperature being at the center of the range, havelow viscosities, and have low drive voltages. Furthermore, the liquidcrystal compositions each contain several types to several tens of typesof compounds for the purpose of optimizing, for example, dielectricanisotropy (Δ∈) and/or birefringence (Δn) for respective displayelements.

In vertical alignment displays, liquid crystal compositions having anegative Δ∈ are used, and in horizontal alignment displays such as theTN-type display, the STN-type display, and the IPS-type display, liquidcrystal compositions having a positive Δ∈ are used. Furthermore, adriving system has also been reported in which a liquid crystalcomposition having a positive Δ∈ is vertically aligned when no voltageis applied, and a display is performed by applying a lateral electricfield. Thus, the need for a liquid crystal composition having a positiveΔ∈ has been further increasing. On the other hand, in all the drivingsystems, low-voltage driving, high-speed response, and a wide operatingtemperature range have been desired. Specifically, a large positiveabsolute value of Δ∈, a low viscosity (η), and a high nematicphase-isotropic liquid phase transition temperature (T_(ni)) have beendesired. Furthermore, it is necessary to control the Δn of a liquidcrystal composition to be in an appropriate range in accordance with acell gap on the basis of a value of Δn×d, which is the product of the Δnand the cell gap (d). In addition, in the case where a liquid crystaldisplay element is applied to a television or the like, high-speedresponsiveness is important and thus a liquid crystal composition havinga small rotational viscosity γ₁ is required.

Liquid crystal compositions containing, as a component of the liquidcrystal compositions, a compound represented by formula (A-1) or (A-2),which is a liquid crystal compound having a positive Δ∈, have beendisclosed (PTL 1 to PTL 4).

In order to practically use a liquid crystal composition in a liquidcrystal display element, it is necessary that no problem occur in termsof display quality. In particular, a liquid crystal composition used inan active-matrix driving liquid crystal display element that is drivenby TFT elements or the like needs to have a high specific resistance ora high voltage holding ratio. In addition, it is also necessary for sucha liquid crystal composition to be stable against external stimuli suchas light and heat. To meet this requirement, antioxidants for improvingstability against heat and liquid crystal compositions containing theantioxidants have been disclosed (refer to PTL 3 and PTL 4). However,the stability is not necessarily sufficient. In particular, liquidcrystal compounds having a large Δ∈ have relatively low stabilityagainst light and heat, and thus such a composition does not havesufficient quality stability.

Furthermore, with the increasing number of applications for liquidcrystal display elements, methods of using the liquid crystal displayelements and methods of producing the liquid crystal display elementshave also been significantly changed. In order to catch up with thesechanges, it has been desired to optimize properties other than knownbasic physical property values. Specifically, regarding liquid crystaldisplay elements that use liquid crystal compositions, verticalalignment (VA)-type liquid crystal display elements, in-plane-switching(IPS)-type liquid crystal display elements, and the like have beenwidely used, and very large display elements having a 50-inch or largerdisplay size have been practically used. Regarding a method forinjecting a liquid crystal composition into a substrate, with theincrease in the size of substrates, a one-drop-fill (ODF) method hasbeen mainly used instead of a known vacuum injection method. However, ithas been found that a drop mark formed when a liquid crystal compositionis dropped on a substrate results in a problem of a decrease in thedisplay quality. In order to form a pre-tilt angle of a liquid crystalmaterial in a liquid crystal display element and to realize high-speedresponsiveness, polymer-stabilized (PS) liquid crystal display elementshave been developed. These display elements are characterized in that amonomer is added to a liquid crystal composition and that the monomer inthe composition is cured. In many cases, the monomer is cured byirradiating the composition with ultraviolet light. Therefore, in thecase where a component having low stability against light is added tothe liquid crystal composition, the specific resistance or the voltageholding ratio is decreased, and in some cases, the generation of a dropmark may also be induced, resulting in a problem of a decrease in theyield of the liquid crystal display element due to display defects.

Accordingly, it has been desired to develop a liquid crystal displayelement which has high stability against light, heat, etc. and in whichdisplay defects such as image sticking and a drop mark do not tend tooccur while maintaining characteristics and performance, such ashigh-speed responsiveness, which are desired for the liquid crystaldisplay element.

CITATION LIST Patent Literature

PTL 1: International Publication No. WO96/032365

PTL 2: Japanese Unexamined Patent Application Publication No. 09-157202

PTL 3: International Publication No. WO98/023564

PTL 4: Japanese Unexamined Patent Application Publication No.2003-183656

PTL 5: Japanese Unexamined Patent Application Publication No. 9-124529

PTL 6: Japanese Unexamined Patent Application Publication No.2006-169472

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a liquid crystalcomposition having a positive dielectric anisotropy (Δ∈), the liquidcrystal composition having a liquid crystal phase over a widetemperature range, a low viscosity, good solubility at low temperatures,a high specific resistance, and a high voltage holding ratio, and beingstable against heat and light. Another object of the present inventionis to provide, by using the liquid crystal composition, for example, anIPS-type or TN-type liquid crystal display element which has highdisplay quality and in which display defects such as image sticking anda drop mark do not tend to occur.

Solution to Problem

The inventor of the present invention studied various liquid crystalcompounds and various chemical substances and found that the objects canbe achieved by combining specific compounds. This finding led to thecompletion of the present invention.

The present invention provides a nematic liquid crystal compositioncontaining, as a first component, at least one compound represented bygeneral formula (I):

(where R¹ represents a linear or branched alkyl group having 1 to 22carbon atoms and at least one CH₂ group in the alkyl group may besubstituted with —O—, —CH═CH—, —CO—, —OCO—, —COO—, —C≡C—, —CF₂O—, or—OCF₂— so that oxygen atoms are not directly adjacent to each other; andM¹ represents a trans-1,4-cyclohexylene group, a 1,4-phenylene group, ora single bond), and

-   as a second component, at least one compound selected from the group    consisting of compounds represented by general formulae (II-a) to    (II-e):

(where R²¹ to R³⁰ each independently represent an alkyl group having 1to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms andX²¹ represents a hydrogen atom or a fluorine atom), wherein a dielectricanisotropy (Δ∈) at 25° C. is +3.5 or more. Furthermore, the presentinvention provides a liquid crystal display element using the liquidcrystal composition.

Advantageous Effects of Invention

According to the liquid crystal composition of the present invention,the liquid crystal composition having a positive Δ∈, a significantly lowviscosity can be achieved, solubility at low temperatures is good, andchanges in the specific resistance and the voltage holding ratio due toheat and light are extremely small, and thus products obtained by usingthe liquid crystal composition can be widely practically used. Liquidcrystal display elements, such as IPS-type and fringe field switching(FFS)-type liquid crystal display elements, using the liquid crystalcomposition are very useful because high-speed response can be achievedand display defects are suppressed.

DESCRIPTION OF EMBODIMENTS

In a liquid crystal composition of the present invention, in a compoundused as a first component and represented by general formula (I):

R¹ represents a linear or branched alkyl group having 1 to 22 carbonatoms and at least one CH₂ group in the alkyl group may be substitutedwith —O—, —CH═CH—, —CO—, —OCO—, —COO—, —C≡C—, —CF₂O—, or —OCF₂— so thatoxygen atoms are not directly adjacent to each other. Examples of R¹preferably include a linear alkyl group, a linear alkoxy group, a linearalkyl group in which one CH₂ group is substituted with —OCO— or —COO—, abranched alkyl group, a branched alkoxy group, and a branched alkylgroup in which one CH₂ group is substituted with —OCO— or —COO—, all ofwhich have 1 to 10 carbon atoms. Examples of R¹ more preferably includea linear alkyl group, a linear alkyl group in which one CH₂ group issubstituted with —OCO— or —COO—, a branched alkyl group, a branchedalkoxy group, and a branched alkyl group in which one CH₂ group issubstituted with —OCO— or —COO—, all of which have 1 to 20 carbon atoms.M¹ represents a trans-1,4-cyclohexylene group, a 1,4-phenylene group, ora single bond. M¹ is preferably a trans-1,4-cyclohexylene group or a1,4-phenylene group.

More specifically, the compound represented by general formula (I) ispreferably a compound selected from compounds represented by generalformulae (I-a) to (I-d) below.

In the above formulae, R¹¹ is preferably a linear alkyl group orbranched alkyl group having 1 to 10 carbon atoms; R¹² is preferably alinear alkyl group or branched alkyl group having 1 to 20 carbon atoms,R¹³ is preferably a linear alkyl group, branched alkyl group, linearalkoxy group, or branched alkoxy group having 1 to 8 carbon atoms; andL¹ is preferably a linear alkylene group or branched alkylene grouphaving 1 to 8 carbon atoms. Among the compounds represented by generalformulae (I-a) to (I-d), the compounds represented by general formulae(I-c) and (I-d) are more preferable.

The liquid crystal composition of the present invention preferablycontains one or two compounds represented by general formula (I), andmore preferably contains one to five compounds represented by generalformula (I). The content thereof is preferably 0.001% to 1% by mass,more preferably 0.001% to 0.1% by mass, and particularly preferably0.001% to 0.05% by mass.

The liquid crystal composition of the present invention contains, as asecond component, at least one compound selected from compoundsrepresented by general formulae (II-a) to (II-e).

In the above formulae, R²¹ to R³⁰ each independently represent an alkylgroup having 1 to 10 carbon atoms or an alkenyl group having 2 to 10carbon atoms. X²¹ represents a hydrogen atom or a fluorine atom. X²¹ ispreferably a fluorine atom. One to ten compounds selected from thecompound group represented by general formula (II) are preferablycontained and one to eight compounds selected from the compound grouprepresented by general formula (II) are particularly preferablycontained. The content thereof is 5% to 80% by mass, preferably 10% to70% by mass, and particularly preferably 20% to 60% by mass.

Preferably, the liquid crystal composition of the present inventionfurther contains, as a third component, at least one compoundrepresented by general formula (III).

In the compound represented by general formula (III), R³¹ represents analkyl group or alkoxy group having 1 to 10 carbon atoms, or an alkenylgroup or alkenyloxy group having 2 to 10 carbon atoms; M³¹ to M³³ eachindependently represent a trans-1,4-cyclohexylene group or a1,4-phenylene group, one or two —CH₂— groups in thetrans-1,4-cyclohexylene group may be substituted with —O— so that oxygenatoms are not directly adjacent to each other, and one or two hydrogenatoms in the phenylene group may be substituted with a fluorine atom;X³¹ and X³² each independently represent a hydrogen atom or a fluorineatom; Z³¹ represents a fluorine atom, a trifluoromethoxy group, or atrifluoromethyl group; n³¹ and n³² each independently represent 0, 1, or2; n³¹+n³² represents 0, 1, or 2; and when plural M³¹s and M³³s arepresent, they may be the same or different.

More specifically, the compound represented by general formula (III) ispreferably a compound selected from compounds represented by generalformulae (III-a) to (III-e) below:

(where R³² represents an alkyl group or alkoxy group having 1 to 10carbon atoms, or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms; X³¹ to X³⁸ each independently represent a hydrogen atom ora fluorine atom; and Z³¹ represents a fluorine atom, a trifluoromethoxygroup, or a trifluoromethyl group.)

One to eight compounds selected from the compound group represented bygeneral formula (III) are preferably contained and one to five compoundsselected from the compound group represented by general formula (III)are particularly preferably contained. The content thereof is 3% to 50%by mass, and preferably 5% to 40% by mass.

The liquid crystal composition of the present invention may furthercontain, as a fourth component, at least one compound selected from thecompound group represented by general formulae (IV-a) to (IV-f):

(where R⁴¹ represents an alkyl group or alkoxy group having 1 to 10carbon atoms, or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms; X⁴¹ to X⁴⁸ each independently represent a hydrogen atom ora fluorine atom; and Z⁴¹ represents a fluorine atom, a trifluoromethoxygroup, or a trifluoromethyl group.) One to ten compounds selected fromthis compound group are preferably contained and one to eight compoundsselected from this compound group are particularly preferably contained.The content thereof is preferably 5% to 50% by mass, and more preferably10% to 40% by mass.

The liquid crystal composition of the present invention has a dielectricanisotropy (Δ∈) of +3.5 or more at 25° C. The Δ∈ is more preferably +3.5to +15.0 at 25° C. The liquid crystal composition of the presentinvention has a birefringence (Δn) of 0.08 to 0.14 at 25° C. The Δn ismore preferably 0.09 to 0.13 at 25° C. More specifically, in the case ofa small cell gap, the Δn is preferably 0.10 to 0.13. In the case of alarge cell gap, the Δn is preferably 0.08 to 0.10. The liquid crystalcomposition of the present invention has a viscosity (η) of 10 to 45mPa·s, more preferably 10 to 25 mPa·s, and particularly preferably 10 to20 mPa·s at 20° C. The liquid crystal composition of the presentinvention has a nematic phase-isotropic liquid phase transitiontemperature (T_(ni)) of 60° C. to 120° C., more preferably 70° C. to100° C., and particularly preferably 70° C. to 85° C.

The liquid crystal composition of the present invention may contain acommon nematic liquid crystal, smectic liquid crystal, cholestericliquid crystal, and the like in addition to the above compounds.

The liquid crystal composition of the present invention may contain apolymerizable compound in order to produce a liquid crystal displayelement such as a polymer-stabilized (PS) mode-, lateral electricfield-type polymer sustained alignment (PSA) mode-, or lateral electricfield-type polymer-stabilized vertical alignment (PSVA)-mode liquidcrystal display element. Examples of the polymerizable compound includephotopolymerizable monomers that are polymerized by energy rays such aslight. In terms of the structure, examples thereof include polymerizablecompounds having a liquid crystal skeleton in which plural six-memberedrings are linked to each other, for example, biphenyl derivatives andterphenyl derivatives. More specifically, a preferable polymerizablecompound is a bifunctional monomer represented by general formula (V):

(where X⁵¹ and X⁵² each independently represent a hydrogen atom or amethyl group;

-   Sp¹ and Sp² each independently represent a single bond, an alkylene    group having 1 to 8 carbon atoms, or —O—(CH₂)_(s)— (where s    represents an integer of 2 to 7 and the oxygen atom is bonded to an    aromatic ring);-   Z⁵¹ represents —OCH₂—, —CH₂O—, —COO—, —OCO—, —CF₂O—, —OCF₂—,    —CH₂CH₂—, —CF₂CF₂—, —CH═CH—COO—, —CH═CH—OCO—, —COO—CH═CH—,    —OCO—CH═CH—, —COO—CH₂CH₂—, —OCO—CH₂CH₂—, —CH₂CH₂—COO—, —CH₂CH₂—OCO—,    —COO—CH₂—, —OCO—CH₂—, —CH₂—COO—, —CH₂—OCO—, —CY¹═CY²— (where Y¹ and    Y² each independently represent a fluorine atom or a hydrogen atom),    —C≡C—, or a single bond; and-   M⁵¹ represents a 1,4-phenylene group, a trans-1,4-cyclohexylene    group, or a single bond, and any hydrogen atom in all the    1,4-phenylene groups in the formula may be substituted with a    fluorine atom.)

Diacrylate derivatives in which each of X⁵¹ and X⁵² represents ahydrogen atom and dimethacrylate derivatives in which each of X⁵¹ andX⁵² represents a methyl group are preferable. Compounds in which one ofX⁵¹ and X⁵² represents a hydrogen atom and the other represents a methylgroup are also preferable. Regarding the rate of polymerization of thesecompounds, the rate of polymerization of the diacrylate derivatives isthe highest, the rate of polymerization of the dimethacrylatederivatives is the lowest, and the rate of polymerization of theasymmetric compounds is between that of the diacrylate derivatives andthat of the dimethacrylate derivatives. Preferable embodiments can beused in accordance with the use of the compound. In a PSA displayelement, the dimethacrylate derivatives are particularly preferable.

Sp¹ and Sp² each independently represent a single bond, an alkylenegroup having 1 to 8 carbon atoms, or —O—(CH₂)_(s)—. In a PSA displayelement, at least one of Sp¹ and Sp² is preferably a single bond. Thatis, embodiments in which each of Sp¹ and Sp² represents a single bond orembodiments in which one of Sp¹ and Sp² represents a single bond and theother represents an alkylene group having 1 to 8 carbon atoms or—O—(CH₂)_(s)— are preferable. In such a case, an alkyl group of 1 to 4is preferable, and s is preferably 1 to 4.

Z⁵¹ is preferably —OCH₂—, —CH₂O—, —COO—, —OCO—, —CF₂O—, —OCF₂—,—CH₂CH₂—, —CF₂CF₂—, or a single bond, more preferably —COO—, —OCO—, or asingle bond, and particularly preferably a single bond.

M⁵¹ represents a 1,4-phenylene group in which any hydrogen atom may besubstituted with a fluorine atom, a trans-1,4-cyclohexylene group, or asingle bond. M⁵¹ is preferably a 1,4-phenylene group or a single bond.When C represents a ring structure other than a single bond, Z⁵¹ may bea linking group other than a single bond. When M⁵¹ is a single bond, Z⁵¹is preferably a single bond.

From the above points, specifically, the ring structure between Sp¹ andSp² in general formula (V) is preferably selected from the structuresdescribed below.

In general formula (V), when M⁵¹ represents a single bond and the ringstructure is formed by two rings, the ring structure representspreferably any one of formulae (Va-1) to (Va-5) below, more preferablyany one of formulae (Va-1) to (Va-3), and particularly preferablyformula (Va-1).

(In the above formulae, both ends are bonded to Sp¹ and Sp².)

Polymerizable compounds having any of these skeletons are most suitablyused in PSA-type liquid crystal display elements in terms of alignmentcontrol force after polymerization, and thus a good alignment state canbe obtained by the polymerizable compounds. Accordingly, displayunevenness is suppressed or no display unevenness is generated.

Accordingly, polymerizable monomers represented by general formulae(V-1) to (V-4) are particularly preferable. Among these, thepolymerizable monomer represented by general formula (V-2) is the mostpreferable.

(In the formulae above, Sp² represents an alkylene group having 2 to 5carbon atoms.)

In the case where a monomer is added to the liquid crystal compositionof the present invention, polymerization proceeds even when nopolymerization initiator is present. However, a polymerization initiatormay be incorporated in order to accelerate the polymerization. Examplesof the polymerization initiator include benzoin ethers, benzophenones,acetophenones, benzyl ketals, and acylphosphine oxides.

To the liquid crystal composition of the present invention, thecomposition containing a polymerizable compound, a liquid crystalalignment capability is provided by polymerizing the polymerizablecompound contained in the liquid crystal composition by irradiation withultraviolet light. The liquid crystal composition of the presentinvention is used in a liquid crystal display element in which theamount of transmitted light is controlled by using the birefringence ofthe liquid crystal composition. The liquid crystal composition of thepresent invention is useful for various liquid crystal display elements,such as an active-matrix liquid crystal display element (AM-LCD), atwisted nematic liquid crystal display element (TN-LCD), a super-twistednematic liquid crystal display element (STN-LCD), an opticallycompensated birefringence liquid crystal display element (OCB-LCD), andan in-plane-switching liquid crystal display element (IPS-LCD). Theliquid crystal composition of the present invention is particularlyuseful for an AM-LCD, and can be used in a transmissive or reflectiveliquid crystal display element.

Two substrates of a liquid crystal cell used in a liquid crystal displayelement may be composed of glass or a flexible transparent material suchas a plastic material. One of the substrates may be composed of anopaque material such as silicon. A transparent substrate having atransparent electrode layer can be produced by, for example, sputteringindium tin oxide (ITO) on a transparent substrate such as a glass plate.

A color filter can be produced by, for example, a pigment dispersionmethod, a printing method, an electrodeposition method, or a stainingmethod. A method for producing a color filter will be described bytaking the pigment dispersion method as an example. First, a curablecoloring composition for a color filter is applied onto theabove-mentioned transparent substrate, and is then patterned. Thecurable coloring composition is then cured by heating or lightirradiation. These steps are performed for each of three colors of red,green, and blue. Thus, pixel portions of the color filter can be formed.Furthermore, pixel electrodes each including an active element such as aTFT, a thin-film diode, or a metal-insulator-metal specific resistanceelement may be provided on the substrate.

The substrates are arranged so as to face each other such that thetransparent electrode layer is disposed inside. In this step, the gapbetween the substrates may be adjusted with a spacer therebetween. Inthis case, the gap is preferably adjusted so that the thickness of alight-modulating layer obtained is in the range of 1 to 100 μm, and morepreferably 1.5 to 10 μm. When a polarizer is used, it is preferable toadjust the product of the birefringence Δn of the liquid crystal and acell thickness d so that the maximum contrast is obtained. When twopolarizers are provided, the polarizing axis of each of the polarizersmay be adjusted so that a satisfactory angle of view and contrast can beobtained. Furthermore, a retardation film for widening the angle of viewmay also be used. Examples of the spacer include glass particles,plastic particles, alumina particles, and a photoresist material.Subsequently, a sealant such as an epoxy thermosetting composition orthe like is applied onto the substrate by screen printing so as to forma liquid-crystal injection port. The substrates are then bonded to eachother, and the sealant is thermally cured by heating.

As a method for interposing the polymerizable compound-containing liquidcrystal composition between two substrates, a commonly used vacuuminjection method, an ODF method, or the like can be employed. In thevacuum injection method, although a drop mark is not generated, thismethod has a problem in that a mark of injection is left. However, inthe present invention, the liquid crystal composition can be suitablyused in a display element produced by using the ODF method.

As a method for polymerizing the polymerizable compound, a method inwhich polymerization is conducted by irradiation with active energy rayssuch as ultraviolet light and an electron beam, which can be used alone,in combination, or sequentially, is preferable because a moderate rateof polymerization is desirable in order to obtain a good alignmentperformance of the liquid crystal. In the case where ultraviolet lightis used, either a polarized light source or an unpolarized light sourcemay be used. When polymerization is conducted in a state in which thepolymerizable compound-containing liquid crystal composition isinterposed between two substrates, it is necessary that at least asubstrate on the irradiation surface side have transparency appropriatefor the active energy rays. Only specific portions may be polymerizedusing a mask during light irradiation, and unpolymerized portions maythen be polymerized by further irradiation with active energy rays whilethe alignment state of the unpolymerized portions is changed by changinga condition such as the electric field, the magnetic field, thetemperature, or the like. In particular, when ultraviolet exposure isperformed, the ultraviolet exposure is preferably performed while analternating electric field is applied to the polymerizablecompound-containing liquid crystal composition. Regarding thealternating electric field applied, an alternating current having afrequency of preferably 10 Hz to 10 kHz, and more preferably 60 Hz to 10kHz is applied, and the voltage applied is selected in accordance with adesired pre-tilt angle of the liquid crystal display element. That is,the pre-tilt angle of the liquid crystal display element can becontrolled by controlling the voltage applied. In a liquid crystaldisplay element of the lateral electric field-type multi-domain verticalalignment (MVA) mode, it is preferable to control the pre-tilt angle to80 to 89.9 degrees from the standpoint of alignment stability and thecontrast.

The temperature during the irradiation is preferably within atemperature range in which the liquid crystal state of the liquidcrystal composition of the present invention is maintained.Polymerization is preferably conducted at a temperature close to roomtemperature, that is, typically at a temperature in the range of 15° C.to 35° C. As a lamp for generating ultraviolet light, a metal halidelamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp,or the like can be used. As for the wavelength of ultraviolet light forirradiation, it is preferable to radiate ultraviolet light in awavelength range which is not included in an absorption wavelength rangeof the liquid crystal composition. Preferably, part of ultraviolet lightis cut off and used, as required. The intensity of ultraviolet light forirradiation is preferably 0.1 mW/cm² to 100 W/cm², and more preferably 2mW/cm² to 50 W/cm². The amount of energy of the ultraviolet light forirradiation can be appropriately adjusted, and is preferably 10 mJ/cm²to 500 J/cm², and more preferably 100 mJ/cm² to 200 J/cm². During theirradiation of ultraviolet light, the intensity of the ultraviolet lightmay be changed. The ultraviolet-irradiation time is appropriatelyselected in accordance with the intensity of the ultraviolet light forirradiation, and is preferably 10 to 3,600 seconds and more preferably10 to 600 seconds.

The liquid crystal display element using the liquid crystal compositionof the present invention is a useful display element which realizes bothhigh-speed response and suppression of display defects. The liquidcrystal display element is particularly useful as a liquid crystaldisplay element for active-matrix driving and can be applied to a liquidcrystal display element for the VA mode, the PSVA mode, the PSA mode,the IPS mode, or the electrically controlled birefringence (ECB) mode.

EXAMPLES

The present invention will be described in more detail by way ofExamples, but the present invention is not limited to these Examples. Itshould be noted that “%” in compositions of Examples and ComparativeExamples described below represents “% by mass”.

Characteristics measured in Examples are as follows:

T_(ni): nematic phase-isotropic liquid phase transition temperature (°C.)

Δn: birefringence at 25° C.

Δ∈: dielectric anisotropy at 25° C.

η: viscosity at 20° C. (mPa·s)

γ₁: rotational viscosity at 25° C. (mPa·s)

VHR: voltage holding ratio (%) at 60° C. at a frequency of 60 Hz and anapplied voltage of 1 V

Image Sticking:

Image sticking of a liquid crystal display element was evaluated asfollows. A predetermined fixed pattern was displayed in a display areafor 1,000 hours, and a uniform image was then displayed on the fullscreen. The level of a residual image of the fixed pattern was evaluatedby visual observation on the basis of the four-level criteria describedbelow.

A: No residual image was observed.

B: A residual image was slightly observed, but was at an acceptablelevel.

C: A residual image was observed, and was at an unacceptable level.

D: A residual image was observed, and was at a very poor level.

Drop Mark:

A drop mark of a liquid crystal display element was evaluated asfollows. When a black color was displayed on the full screen, a dropmark appearing as a white portion was evaluated by visual observation onthe basis of the four-level criteria described below.

A: No residual image was observed.

B: A residual image was slightly observed, but was at an acceptablelevel.

C: A residual image was observed, and was at an unacceptable level.

D: A residual image was observed, and was at a very poor level.

In the description of compounds in Examples, the abbreviations below areused.

(Ring Structure)

(Side Chain Structure and Linking Structure)

TABLE 1 n (number) at end C_(n)H_(2n+1)— -2- —CH₂Ch₂— -10- —CH₂O— -01-—OCH₂— —V— —CO— —VO— —COO— —CFFO— —CF₂O— —F —F —Cl —Cl —CN —C≡N —OCFFF—OCF₃ —CFFF —CF₃ -On —OC_(n)H_(2n+1) -T- —C≡C— ndm-C_(n)H_(2n+1)—HC═CH—(CH₂)_(m−1)— -ndm —(CH₂)_(n−1)—HC═CH—C_(m)H_(2m+1)ndmO— C_(n)H_(2n+1)—HC═CH—(CH₂)_(m−1)O— —Ondm—O—(CH₂)_(n−1)—HC=CH—C_(m)H_(2m+1) -ndm- —(CH₂)_(n−1)—HC═CH—(CH₂)_(m−1)—

Example 1

A liquid crystal composition LC-1 shown below was prepared.

[Chem. 14] Chemical structure Ratio Abbreviation

48%  3-Cy-Cy-1d0

4% 3-Cy-Cy-1d1

8% 1-Ph—Ph-3d1

5% 3-Cy-Ph—Ph-2

5% 2-Ph—Ph1—Ph-3

2% 3-Ph—Ph3—CFFO—Ph3—F

3% 3-Cy-Cy-CFFO—Ph3—F

7% 3-Ph—Ph1—Ph3—CFFO—Ph3—F

5% 4-Cy-Cy-Ph3—CFFO—Ph3—F

The values of the physical properties of LC-1 were as follows.

TABLE 2 T_(NI)/° C. 75.8 Δn 0.112 no 1.488 ε_(⊥) 5.5 Δε 2.9 η/mPa · s13.5

A liquid crystal composition LCM-1 was prepared by adding 0.03% of acompound represented by formula (I-c-1):

to 99.97% of the liquid crystal composition LC-1. The values of thephysical properties of LCM-1 were substantially the same as those ofLC-1. The initial VHR of the liquid crystal composition LCM-1 was 99.3%,whereas the VHR after the composition LCM-1 was left to stand at a hightemperature of 150° C. for one hour was 98.9%. An in-plane-switching(IPS) liquid crystal display element was prepared by using the liquidcrystal composition LCM-1, and image sticking and a drop mark of theliquid crystal display element were evaluated by the methods describedabove. Good results were obtained as shown below.

TABLE 3 Evaluation of drop mark A Evaluation of image sticking A

Comparative Example 1

The liquid crystal composition LC-1, to which the compound representedby formula (I-c-1) described in Example 1 was not added, had an initialVHR of 99.5%. In contrast, the VHR after the composition LC-1 was leftto stand at a high temperature of 150° C. for one hour was 87.2%, whichwas significantly decreased from the initial VHR.

A vertical alignment (VA) liquid crystal display element was prepared byusing the liquid crystal composition LC-1, and image sticking and a dropmark of the liquid crystal display element were evaluated by the methodsdescribed above. Results inferior to those of Example 1 were obtained asshown below.

TABLE 4 Evaluation of drop mark C Evaluation of image sticking D

Comparative Example 2

A liquid crystal composition LC-2 that did not contain a compoundrepresented by general formula (II), the composition LC-2 being shownbelow, was prepared.

[Chem. 16] Chemical structure Ratio Abbreviation

27% 4-Cy-VO—Ph-1

20% 5-Cy-VO—Ph-1

20% 5-Cy-VO—Ph-3

 8% 3-Ph—Ph3—CFFO—Ph3—F

13% 3-Cy-Cy-CFFO—Ph3—F

12% 3-Ph—Ph1—Ph3—CFFO—Ph3—F

The values of the physical properties of LC-2 were as follows.

TABLE 5 T_(NI)/° C. 69.3 Δn 0.096 no 1.484 ε_(⊥) 5.5 Δε 4.8 η/mPa · s30.3

A liquid crystal composition LCM-A was prepared by adding 0.03% of thecompound represented by formula (I-c-1) to 99.97% of the liquid crystalcomposition LC-A. The values of the physical properties of LCM-A weresubstantially the same as those of LC-A. The results showed that theliquid crystal composition LCM-A, which did not contain a compoundrepresented by general formula (II), had a viscosity η significantlyhigher than that of the liquid crystal composition LCM-1, whichcontained a compound represented by general formula (II). The initialVHR of the liquid crystal composition LCM-A was 92.3%, whereas the VHRafter the composition LCM-A was left to stand at a high temperature of150° C. for one hour was 67.4%.

An IPS liquid crystal display element was prepared by using the liquidcrystal composition LCM-A, and image sticking and a drop mark of theliquid crystal display element were evaluated by the methods describedabove. Results inferior to those of Example 1 were obtained as shownbelow.

TABLE 6 Evaluation of drop mark D Evaluation of image sticking D

Examples 2 to 4

Liquid crystal compositions LC-2 to LC-4 shown below were prepared, andthe values of the physical properties of LC-2 to LC-4 were measured. Theresults are shown in the table below.

TABLE 7 T_(NI)/° C. 101 T_(NI)/° C. 100.7 T_(NI)/° C. 103.2 Δn 0.095 Δn0.094 Δn 0.102 Δε 8.2 Δε 8.0 Δε 7.1 η/mPa · s 23.6 η/mPa · s 22.2 η/mPa· s 20.8 γ₁/mPa · s 115 γ₁/mPa · s 108 γ₁/mPa · s 96 4-Cy-Cy-1d0 15% 4-Cy-Cy-1d0 15%  5-Cy-Cy-1d0  5% 0d1-Cy-Cy-Ph-1 4% 0d1-Cy-Cy-Ph-1 4%3-Cy-Cy-1d1 10% 0d3-Cy-Cy-Ph-1 14%  0d3-Cy-Cy-Ph-1 14%  0d1-Cy-Cy-Ph-18% 3-Cy-Ph—Ph-Cy-3 3% 3-Cy-Ph—Ph-Cy-3 3% 5-Cy-Cy-Ph—O1 6%3-Cy-Ph—Ph1-Cy-3 4% 3-Cy-Ph—Ph1-Cy-3 4% 2-Ph—Ph1—Ph-3 8% 1-Cy-Cy-Ph3—F9% 1-Cy-Cy-Ph3—F 9% 2-Cy-Cy-Ph3—F 11%  2-Cy-Cy-Ph3—F 10%  2-Cy-Cy-Ph3—F10%  3-Cy-Cy-Ph3—F 15%  3-Cy-Cy-Ph3—F 10%  3-Cy-Cy-Ph3—F 10% 5-Cy-Cy-Ph3—F 5% 5-Cy-Cy-Ph3—F 5% 5-Cy-Cy-Ph3—F 5% 3-Cy-Ph—Ph3—F 6%3-Cy-Ph1—Ph3—F 8% 0d1-Cy-Cy-Ph1—F 8% 3-Cy-Ph—Ph1—F 9% 5-Cy-Ph1—Ph3—F 7%3-Cy-Cy-Ph1—Ph3—F 8% 4-Cy-Cy-Ph—OCFFF 4% 3-Ph—Ph1—Ph3—F 3%2-Ph—Ph3—CFFO—Ph3—F 4% 3-Cy-Cy-CFFO—Ph3—F 7% 3-Cy-Cy-Ph1—Ph3—F 8%3-Ph—Ph3—CFFO—Ph3—F 6% 5-Cy-Cy-CFFO—Ph3—F 4% 3-Cy-Cy-Ph1—Ph3—F 2%

Liquid crystal compositions LCM-2 to LCM-4 were respectively prepared byadding 0.03% of the compound represented by formula (I-c-1) to 99.97% ofthe liquid crystal compositions LC-2 to LC-4. The values of the physicalproperties of LCM-2 to LCM-4 were substantially the same as those beforethe addition of the compound.

The initial VHR of each of the liquid crystal compositions LCM-2 toLCM-4 was substantially the same as the VHR after the composition wasleft to stand at a high temperature of 150° C. for one hour. IPS liquidcrystal display elements were prepared by using the liquid crystalcompositions LCM-2 to LCM-4, and image sticking and a drop mark of eachof the liquid crystal display elements were evaluated. Good results wereobtained as shown below.

TABLE 8 LCM-2 LCM-3 LCM-4 Initial VHR (%) 98.6 98.6 98.5 VHR (%) after 1hour at 150° C. 98.2 98.3 98.1 Evaluation of drop mark A A A Evaluationof image sticking A A A

Examples 5 to 7

Liquid crystal compositions LC-5 to LC-7 shown below were prepared, andthe values of the physical properties of LC-5 to LC-7 were measured. Theresults are shown in the table below.

TABLE 9 T_(NI)/° C. 90.2 T_(NI)/° C. 110 T_(NI)/° C. 77.4 Δn 0.098 Δn0.0990 Δn 0.1010 Δε 9.1 Δε 8.3 Δε 7.0 η/mPa · s 18.1 η/mPa · s 23.4η/mPa · s 14.2 γ₁/mPa · s 90 γ₁/mPa · s 112 γ₁/mPa· s 86 5-Cy-Cy-1d015%  5-Cy-Cy-1d0 10%  5-Cy-Cy-1d0 12%  3-Cy-Cy-1d1 2% 3-Cy-Cy-1d1 5%3-Cy-Cy-1d0 25%  0d1-Cy-Cy-Ph-1 12%  0d1-Cy-Cy-Ph-1 8% 3-Cy-Cy-1d1 12% 2-Ph—Ph1—Ph-3 3% 0d3-Cy-Cy-Ph-1 12%  0d1-Cy-Cy-Ph-1 4% 2-Ph—Ph1—Ph-4 3%2-Ph—Ph1—Ph-5 2% 0d3-Cy-Cy-Ph-1 9% 2-Cy-Cy-Ph3—F 8% 3-Cy-Ph—Ph-Cy-3 3%2-Ph—Ph1—Ph3—F 5% 2-Cy-Ph—Ph3—F 3% 3-Cy-Ph—Ph1-Cy-3 3% 3-Ph—Ph1—Ph3—F 9%3-Cy-Ph—Ph3—F 9% 1-Cy-Cy-Ph3—F 9% 2-Ph—Ph3—CFFO—Ph3—F 4%4-Cy-Cy-Ph—OCFFF 14%  2-Cy-Cy-Ph3—F 10%  3-Ph—Ph3—CFFO—Ph3—F 6%3-Ph—Ph3—CFFO—Ph3—F 11%  3-Cy-Cy-Ph3—F 6% 3-Cy-Cy-CFFO—Ph3—F 2%2-Cy-Cy-CFFO—Ph3—F 9% 5-Cy-Cy-Ph3—F 5% 5-Cy-Cy-CFFO—Ph3—F 3%3-Cy-Cy-CFFO—Ph3—F 8% 0d1-Cy-Cy-Ph1—F 8% 3-Cy-Cy-Ph1—Ph3—F 9%3-Cy-Cy-Ph1—Ph3—F 3% 2-Ph—Ph3—CFFO—Ph3—F 4% 3-Ph—Ph3—CFFO—Ph3—F 6%3-Cy-Cy-Ph1—Ph3—F 9%

Liquid crystal compositions LCM-5 to LCM-7 were respectively prepared byadding 0.03% of the compound represented by formula (I-c-1) to 99.97% ofthe liquid crystal compositions LC-5 to LC-7. The values of the physicalproperties of LCM-5 to LCM-7 were substantially the same as those beforethe addition of the compound.

The initial VHR of each of the liquid crystal compositions LCM-5 toLCM-7 was substantially the same as the VHR after the composition wasleft to stand at a high temperature of 150° C. for one hour. IPS liquidcrystal display elements were prepared by using the liquid crystalcompositions LCM-5 to LCM-7, and image sticking and a drop mark of eachof the liquid crystal display elements were evaluated. Good results wereobtained as shown below.

TABLE 10 LCM-5 LCM-6 LCM-7 Initial VHR (%) 98.4 98.5 98.4 VHR (%) after1 hour at 150° C. 98.1 98.3 98.0 Evaluation of drop mark A A AEvaluation of image sticking A A A

Examples 8 to 10

Liquid crystal compositions LC-8 to LC-10 shown below were prepared, andthe values of the physical properties of LC-8 to LC-10 were measured.The results are shown in the table below.

TABLE 11 T_(NI)/° C. 76.0 T_(NI)/° C. 81.8 T_(NI)/° C. 75.0 Δn 0.097 Δn0.099 Δn 0.112 Δε 6.8 Δε 8.0 Δε 8.7 η/mPa · s 14.5 η/mPa · s 14.6 η/mPa· s 15.2 γ₁/mPa · s 83 γ₁/mPa · s 83 γ₁/mPa · s 87 3-Cy-Cy-1d0 38% 3-Cy-Cy-1d0 38%  3-Cy-Cy-1d0 30%  3-Cy-Cy-1d1 9% 3-Cy-Cy-1d1 14% 3-Cy-Cy-1d1 17%  0d1-Cy-Cy-Ph-1 16%  0d3-Cy-Cy-Ph-1 8% 0d1-Cy-Cy-Ph-1 7%0d3-Cy-Cy-Ph-1 4% 3-Ph—Ph3—CFFO—Ph3—F 9% 0d3-Cy-Cy-Ph-1 7%2-Ph—Ph3—CFFO—Ph3—F 2% 3-Cy-Cy-CFFO—Ph3—F 15%  3-Cy-Cy-Ph-2 2%3-Ph—Ph3—CFFO—Ph3—F 12%  3-Ph—Ph1—Ph3—CFFO—Ph3—F 2% 2-Ph—Ph1—Ph-4 2%3-Cy-Cy-CFFO—Ph3—F 7% 4-Ph—Ph1—Ph3—CFFO—Ph3—F 7% 2-Ph—Ph1—Ph3—F 8%3-Ph—Ph—Ph1—Ph3—F 1% 5-Ph—Ph1—Ph3—CFFO—Ph3—F 7% 3-Ph—Ph1—Ph3—F 12% 3-Ph—Ph1—Ph3—CFFO—Ph3—F 2% 3-Ph—Ph3—Ph3—F 4% 2-Py-Ph—Ph3—CFFO—Ph3—F 3%3-Cy-Cy-Ph1—CFFO—Ph3—F 11%  2-Py-Ph—Ph3—CFFO—Ph3—F 6%

Liquid crystal compositions LCM-8 to LCM-10 were respectively preparedby adding 0.03% of the compound represented by formula (I-c-1) to 99.97%of the liquid crystal compositions LC-8 to LC-10. The values of thephysical properties of LCM-8 to LCM-10 were substantially the same asthose before the addition of the compound.

The initial VHR of each of the liquid crystal compositions LCM-8 toLCM-10 was substantially the same as the VHR after the composition wasleft to stand at a high temperature of 150° C. for one hour. IPS liquidcrystal display elements were prepared by using the liquid crystalcompositions LCM-8 to LCM-10, and image sticking and a drop mark of eachof the liquid crystal display elements were evaluated. Good results wereobtained as shown below.

TABLE 12 LCM-8 LCM-9 LCM-10 Initial VHR (%) 98.5 98.6 98.6 VHR (%) after1 hour at 150° C. 98.2 98.3 98.2 Evaluation of drop mark A A AEvaluation of image sticking A A A

Examples 11 to 13

Liquid crystal compositions LC-11 to LC-13 shown below were prepared,and the values of the physical properties of LC-11 to LC-13 weremeasured. The results are shown in the table below.

TABLE 13 T_(NI)/° C. 76.0 T_(NI)/° C. 77.2 T_(NI)/° C. 77.9 Δn 0.114 Δn0.135 Δn 0.131 Δε 6.0 Δε 4.5 Δε 4.6 η/mPa · s 13.3 η/mPa · s 10.5 η/mPa· s 12.4 γ₁/mPa · s 77 γ₁/mPa · s 57 γ₁/mPa · s 74 3-Cy-Cy-1d0 39% 2-Cy-Cy-1d0 32%  3-Cy-Cy-1d0 44%  3-Cy-Cy-1d1 7% 0d1-Cy-Cy-Ph-1 4%3-Cy-Cy-1d1 3% 0d1-Cy-Cy-Ph-1 11%  2-Ph—Ph1—Ph-3 10%  2-Ph—Ph-3d1 13% 2-Ph—Ph1—Ph-3 8% 2-Ph—Ph1—Ph-5 11%  3-Cy-Ph—Ph-2 7% 2-Ph—Ph1—Ph-5 8%3-Ph—Ph1—Ph-5 7% 2-Ph—Ph1—Ph-3 8% 3-Ph—Ph3—CFFO—Ph3—F 10%  2-Cy-Cy-Ph—F6% 3-Ph—Ph1—Ph-3 7% 3-Cy-Cy-Ph—Ph3—F 6% 3-Cy-Cy-Ph—F 21% 3-Ph—Ph1—Ph3—CFFO—Ph3—F 9% 4-Ph—Ph1—Ph3—CFFO—Ph3—F 11%  5-Cy-Ph—Ph—F 7%4-Cy-Cy-Ph1—CFFO—Ph3—F 3% 3-Cy-Ph—Ph3—F 2% 3-Cy-Ph3—Ph1—OCFFF 6%

Liquid crystal compositions LCM-11 to LCM-13 were respectively preparedby adding 0.03% of the compound represented by formula (I-c-1) to 99.97%of the liquid crystal compositions LC-11 to LC-13. The values of thephysical properties of LCM-11 to LCM-13 were substantially the same asthose before the addition of the compound.

The initial VHR of each of the liquid crystal compositions LCM-11 toLCM-13 was substantially the same as the VHR after the composition wasleft to stand at a high temperature of 150° C. for one hour. IPS liquidcrystal display elements were prepared by using the liquid crystalcompositions LCM-11 to LCM-13, and image sticking and a drop mark ofeach of the liquid crystal display elements were evaluated. Good resultswere obtained as shown below.

TABLE 14 LCM-11 LCM-12 LCM-13 Initial VHR (%) 98.7 98.6 98.8 VHR (%)after 1 hour at 150° C. 98.4 98.4 98.5 Evaluation of drop mark A A AEvaluation of image sticking A A A

Examples 14 to 16

Liquid crystal compositions LC-14 to LC-16 shown below were prepared,and the values of the physical properties of LC-14 to LC-16 weremeasured. The results are shown in the table below.

TABLE 15 T_(NI)/° C. 80.6 T_(NI)/° C. 74.9 T_(NI)/° C. 80.0 Δn 0.122 Δn0.121 Δn 0.110 Δε 6.0 Δε 4.1 Δε 5.9 η/mPa · s 11.1 η/mPa · s 10.8 η/mPa· s 11.6 γ₁/mPa · s 65 γ₁/mPa · s 60 γ₁/mPa · s 68 3-Cy-Cy-1d0 47% 3-Cy-Cy-1d0 29%  3-Cy-Cy-1d0 10%  3-Cy-Cy-1d1 9% 5-Cy-Cy-0d1 8%3-Cy-Cy-1d1 6% 3-Cy-Cy-Ph-2 7% 3-Cy-Cy-1d1 13%  3-Cy-Cy-1d1-F 28% 2-Ph—Ph1—Ph-3 4% 5-Ph—Ph-1 2% 0d1-Cy-Cy-Ph-1 11%  2-Ph—Ph1—Ph-5 7%2-Ph—Ph1—Ph-3 6% 0d3-Cy-Cy-Ph-1 10%  3-Cy-Ph—Ph-Cy-3 2% 2-Ph—Ph1—Ph-4 6%2-Ph—Ph1—Ph-3 10%  2-Ph—Ph1—Ph-3 6% 2-Ph—Ph1—Ph-5 6% 2-Ph—Ph1—Ph-5 10% 3-Ph—Ph1—Ph-3 7% 3-Cy-Ph—Ph-Cy-3 4% 5-Cy-Ph—Ph1—Ph-2 2%3-Ph—Ph3—CFFO—Ph3—F 2% 3-Ph—Ph1—Ph3—F 9% 3-Ph—Ph3—CFFO—Ph3—F 7%3-Cy-Cy-Ph1—Ph3—F 2% 2-Ph—Ph3—Ph3—F 7% 3-Cy-Cy-Ph1—CFFO—Ph3—F 6%3-Cy-Ph—Ph3—Ph1—OCFFF 7% 3-Ph—Ph3—CFFO—Ph3—F 4% 3-Cy-Ph—Cl 3%3-Cy-Cy-Ph1—Ph3—F 3%

Liquid crystal compositions LCM-14 to LCM-16 were respectively preparedby adding 0.03% of the compound represented by formula (I-c-1) to 99.97%of the liquid crystal compositions LC-14 to LC-16. The values of thephysical properties of LCM-14 to LCM-16 were substantially the same asthose before the addition of the compound.

The initial VHR of each of the liquid crystal compositions LCM-14 toLCM-16 was substantially the same as the VHR after the composition wasleft to stand at a high temperature of 150° C. for one hour. IPS liquidcrystal display elements were prepared by using the liquid crystalcompositions LCM-14 to LCM-16, and image sticking and a drop mark ofeach of the liquid crystal display elements were evaluated. Good resultswere obtained as shown below.

TABLE 16 LCM-14 LCM-15 LCM-16 Initial VHR (%) 98.9 98.7 98.9 VHR (%)after 1 hour at 150° C. 98.6 98.4 98.5 Evaluation of drop mark A A AEvaluation of image sticking A A A

Example 17

A polymerizable liquid crystal composition CLCM-1 was prepared by adding0.3% of a polymerizable compound represented by formula (IV-b):

to 99.7% of the nematic liquid crystal composition LCM-1 described inExample 1, and uniformly dissolving the polymerizable compound. Thevalues of the physical properties of CLCM-1 were substantially the sameas those of the nematic liquid crystal composition described inExample 1. The CLCM-2 was injected, by a vacuum injection method, into acell with ITO, the cell having a cell gap of 3.5 μm and includingpolyimide alignment layers that induced homogeneous alignment. Theliquid crystal cell was then irradiated with ultraviolet light using ahigh-pressure mercury lamp through a filter that cut ultraviolet lightof 320 nm or less while a square wave at a frequency of 1 kHz wasapplied to the cell. The irradiation intensity on the surface of thecell was adjusted to 10 mW/cm², and the irradiation was performed for600 seconds, thus fabricating a horizontal-alignment liquid crystaldisplay element in which the polymerizable compound in the polymerizableliquid crystal composition was polymerized. It was confirmed that aforce to control the alignment of the liquid crystal compound wasgenerated by the polymerization of the polymerizable compound.

The invention claimed is:
 1. A nematic liquid crystal compositioncomprising: as a first component, at least one compound represented bygeneral formula (I):

where R¹ represents a linear or branched alkyl group having 1 to 22carbon atoms and one CH₂ group in the alkyl group may be substitutedwith —O—; and M¹ represents a trans-1,4-cyclohexylene group; and as asecond component, at least one compound selected from the groupconsisting of compounds represented by general formulae (II-a) to(II-e):

where R²¹ to R³⁰ each independently represent an alkyl group having 1 to10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms and X²¹represents a hydrogen atom or a fluorine atom, wherein a dielectricanisotropy (Δ∈) at 25° C. is +3.5 or more.
 2. The nematic liquid crystalcomposition according to claim 1, further comprising, as a thirdcomponent, at least one compound represented by general formula (III):

where R³¹ represents an alkyl group or alkoxy group having 1 to 10carbon atoms, or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms; M³¹ to M³³ each independently represent atrans-1,4-cyclohexylene group or a 1,4-phenylene group, one or two —CH2-groups in the trans-1,4-cyclohexylene group may be substituted with —O—so that oxygen atoms are not directly adjacent to each other, and one ortwo hydrogen atoms in the phenylene group may be substituted with afluorine atom; X³¹ and X³² each independently represent a hydrogen atomor a fluorine atom; Z³¹ represents a fluorine atom, a trifluoromethoxygroup, or a trifluoromethyl group; n³¹ and n³² each independentlyrepresent 0, 1, or 2; n³¹+n³² represents 0, 1, or 2; and when pluralM³¹s and M³³s are present, they may be the same or different.
 3. Thenematic liquid crystal composition according to claim 2, wherein generalformula (III) is represented by any one of general formulae (III-a) to(III-e):

where R³² represents an alkyl group or alkoxy group having 1 to 10carbon atoms, or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms; X³¹ to X³⁸ each independently represent a hydrogen atom ora fluorine atom; and Z³¹ represents a fluorine atom, a trifluoromethoxygroup, or a trifluoromethyl group.
 4. The nematic liquid crystalcomposition according to claim 3, further comprising at least onecompound selected from the group consisting of compounds represented bygeneral formulae (IV-a) to (IV-f):

where R⁴¹ represents an alkyl group or alkoxy group having 1 to 10carbon atoms, or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms; X⁴¹ to X⁴⁸ each independently represent a hydrogen atom ora fluorine atom; and Z⁴¹ represents a fluorine atom, a trifluoromethoxygroup, or a trifluoromethyl group.
 5. The nematic liquid crystalcomposition according to claim 4, wherein, in general formula (I), R¹represents a linear or branched alkyl group having 1 to 10 carbon atoms.6. The nematic liquid crystal composition according to claim 5, whereinthe content of the at least one compound represented by general formula(I) is 0.001% to 1% by mass, and the content of the at least onecompound represented by general formula (II) is 10% to 70% by mass. 7.The nematic liquid crystal composition according to claim 6, furthercomprising a polymerizable compound represented by general formula (V):

where X⁵¹ and X⁵² each independently represent a hydrogen atom or amethyl group; Sp¹ and Sp² each independently represent a single bond, analkylene group having 1 to 8 carbon atoms, or —O—(CH₂)_(s)— where srepresents an integer of 2 to 7 and the oxygen atom is bonded to anaromatic ring; Z⁵¹ represents —OCH₂—, —CH₂O—, —COO—, —OCO—, —CF₂O—,—OCF₂—, —CH₂CH₂—, —CF₂CF₂—, —CH═CH—COO—, —CH═CH—OCO—, —COO—CH═CH—,—OCO—CH═CH—, —COO—CH₂CH₂—, —OCO—CH₂CH₂—, —CH₂CH₂—COO—, —CH₂CH₂—OCO—,—COO—CH₂—, —OCO—CH₂—, —CH₂—COO—, —CH₂—OCO—, —CY¹═CY²— (where Y¹ and Y²each independently represent a fluorine atom or a hydrogen atom), —C≡C—,or a single bond; and M⁵¹ represents a 1,4-phenylene group, atrans-1,4-cyclohexylene group, or a single bond, and any hydrogen atomin all the 1,4-phenylene groups in the formula may be substituted with afluorine atom.
 8. A liquid crystal display element for active-matrixdriving, the liquid crystal display element comprising the liquidcrystal composition according to claim
 7. 9. A liquid crystal displayelement for an IPS mode, an FFS mode, or a VA-IPS mode, the liquidcrystal display element comprising the liquid crystal compositionaccording to claim
 7. 10. A polymer-stabilized mode liquid crystaldisplay element produced by using the nematic liquid crystal compositionaccording to claim 7, the liquid crystal composition containing apolymerizable compound, and polymerizing the polymerizable compoundcontained in the liquid crystal composition with or without applicationof a voltage.
 11. The nematic liquid crystal composition according toclaim 1, wherein the first component further comprises a compoundrepresented by the formula (1-b):

wherein R¹² is a linear alkyl group or branched alkyl group having 1 to20 carbon atoms, and L¹ is a linear alkylene group or branched alkylenegroup having 1 to 8 carbon atoms.
 12. The nematic liquid crystalcomposition according to claim 1, wherein the first component isrepresented by the formula (1-c):

wherein R¹³ is a linear alkyl group, branched alkyl group, linear alkoxygroup, or branched alkoxy group having 1 to 8 carbon atoms.
 13. Thenematic liquid crystal composition according to claim 1, wherein thefirst component is represented by the formula (1-c-1)


14. A nematic liquid crystal composition comprising: as a firstcomponent, at least one compound represented by general formula (I):

where R¹ represents a linear or branched alkyl group having 1 to 22carbon atoms and one CH₂ group in the alkyl group may be substitutedwith —O—; and M¹ represents a trans-1,4-cyclohexylene group; as a secondcomponent, at least one compound selected from the group consisting ofcompounds represented by general formulae (II-a) to (II-e):

where R²¹ to R³⁰ each independently represent an alkyl group having 1 to10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms and X²¹represents a hydrogen atom or a fluorine atom, wherein a dielectricanisotropy (Δ∈) at 25° C. is +3.5 or more, and a third component, atleast one compound represented by general formula (III):

where R³¹ represents an alkyl group or alkoxy group having 1 to 10carbon atoms, or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms; M³¹ to M³³ each independently represent atrans-1,4-cyclohexylene group or a 1,4-phenylene group, one or two —CH2-groups in the trans-1,4-cyclohexylene group may be substituted with —O—so that oxygen atoms are not directly adjacent to each other, and one ortwo hydrogen atoms in the phenylene group may be substituted with afluorine atom; X³¹ and X³² each represent a fluorine atom; Z³¹represents a fluorine atom; n³¹ and n³² each independently represent 0,1, or 2; n³¹+n³² represents 0, 1, or 2; and when plural M³¹s and M³³sare present, they may be the same or different.
 15. The nematic liquidcrystal composition according to claim 14, wherein general formula (III)is represented by any one of general formulae (III-a) to (III-e):

where R³² represents an alkyl group or alkoxy group having 1 to 10carbon atoms, or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms; X³¹ to X³² each represent a fluorine atom, X³³ to X³⁸ eachindependently represent a hydrogen atom or a fluorine atom; and Z³¹represents a fluorine atom, a trifluoromethoxy group, or atrifluoromethyl group.
 16. The nematic liquid crystal compositionaccording to claim 15, further comprising at least one compound selectedfrom the group consisting of compounds represented by general formulae(IV-a) to (IV-f):

where R⁴¹ represents an alkyl group or alkoxy group having 1 to 10carbon atoms, or an alkenyl group or alkenyloxy group having 2 to 10carbon atoms; X⁴¹ to X⁴⁸ each independently represent a hydrogen atom ora fluorine atom; and Z⁴¹ represents a fluorine atom, a trifluoromethoxygroup, or a trifluoromethyl group.
 17. The nematic liquid crystalcomposition according to claim 16, further comprising a polymerizablecompound represented by general formula (V):

where X⁵¹ and X⁵² each independently represent a hydrogen atom or amethyl group; Sp¹ and Sp² each independently represent a single bond, analkylene group having 1 to 8 carbon atoms, or —O—(CH₂)_(s)— where srepresents an integer of 2 to 7 and the oxygen atom is bonded to anaromatic ring; Z⁵¹ represents —OCH₂—, —CH₂O—, —COO—, —OCO—, —CF₂O—,—OCF₂—, —CH₂CH₂—, —CF₂CF₂—, —CH═CH—COO—, —CH═CH—OCO—, —COO—CH═CH—,—OCO—CH═CH—, —COO—CH₂CH₂—, —OCO—CH₂CH₂—, —CH₂CH₂—COO—, —CH₂CH₂—OCO—,—COO—CH₂—, —OCO—CH₂—, —CH₂—COO—, —CH₂—OCO—, —CY¹═CY²— (where Y¹ and Y²each independently represent a fluorine atom or a hydrogen atom), —C≡C—,or a single bond; and M⁵¹ represents a 1,4-phenylene group, atrans-1,4-cyclohexylene group, or a single bond, and any hydrogen atomin all the 1,4-phenylene groups in the formula may be substituted with afluorine atom.
 18. A polymer-stabilized mode liquid crystal displayelement produced by using the nematic liquid crystal compositionaccording to claim 17, the liquid crystal composition containing apolymerizable compound, and polymerizing the polymerizable compoundcontained in the liquid crystal composition with or without applicationof a voltage.
 19. The nematic liquid crystal composition according toclaim 14, wherein the first component further comprises a compoundrepresented by the formula (1-b):

wherein R¹² is a linear alkyl group or branched alkyl group having 1 to20 carbon atoms, and L¹ is a linear alkylene group or branched alkylenegroup having 1 to 8 carbon atoms.
 20. The nematic liquid crystalcomposition according to claim 14, wherein the second componentcomprises a compound represented by general formula (II-a)

and wherein the third component comprises at least one compound selectedfrom the group consisting of compounds represented by general formulae(III-b), (III-d) and (III-e)

where R²¹ to R²² each independently represent an alkyl group having 1 to10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, R³²represents an alkyl group or alkoxy group having 1 to 10 carbon atoms,or an alkenyl group or alkenyloxy group having 2 to 10 carbon atoms; X³¹to X³² each represent a fluorine atom, X³³ to X³⁸ each independentlyrepresent a hydrogen atom or a fluorine atom; and Z³¹ represents afluorine atom.